CN111454446A - Method for preparing polyphenylene ether and polyphenylene ether prepared by the same - Google Patents

Abstract

The present invention relates to a method for preparing polyphenylene ether and polyphenylene ether prepared therefrom. Specifically, the present invention discloses a method for preparing polyphenylene ether, which comprises feeding air into a continuous flow reactor containing a reaction mixture comprising phenol, a transition metal catalyst and an organic solvent, and oxidatively polymerizing the reaction mixture at a prescribed temperature and pressure to form polyphenylene ether. The residence time of the reaction mixture in the continuous flow reactor is less than or equal to 30 min. Also disclosed are polyphenylene ethers prepared by the method and articles comprising the polyphenylene ethers.

Description

Method for preparing polyphenylene ether and polyphenylene ether prepared by the same

Technical Field

The present invention relates to the field of polyphenylene ethers.

Background

Polyphenylene ethers are a class of engineering thermoplastics that are of high interest due to their chemical and physical properties. Polyphenylene ethers can be prepared by the oxidative coupling of phenol with oxygen in the presence of a catalyst (e.g., a copper amine catalyst). A typical method for preparing polyphenylene ethers is based on a batch process. Limitations that batch operations may be subject to include batch-to-batch product quality differences. Accordingly, there remains a need in the art for an improved process for the preparation of polyphenylene ethers which provides a polymer product having a reduced reaction time.

Disclosure of Invention

A method for preparing polyphenylene ether comprises feeding air into a continuous flow reactor containing a reaction mixture comprising phenol, a transition metal catalyst and an organic solvent; then oxidizing the polymerization reaction mixture at a temperature of 20 to 60 ℃, preferably 25 to 55 ℃, more preferably 30 to 50 ℃ and a pressure of more than 150kPa, preferably more than or equal to 200kPa, more preferably more than or equal to 500kPa, more preferably more than or equal to 1000kPa to form a polyphenylene ether; wherein the residence time of the reaction mixture in the continuous flow reactor is less than or equal to 30min, preferably 3 to 20min, more preferably 3 to 15 min.

A polyphenylene ether is prepared by the method.

An article comprises the polyphenylene ether.

The above described and other features are exemplified by the following detailed description.

Detailed Description

The present inventors have advantageously discovered a process for preparing polyphenylene ether using a continuous flow reactor employing short residence times (e.g., ≦ 30min), low metal catalyst concentrations, and using air as the oxidant. Continuous process methods can provide advantages such as reduced operating costs compared to batch production. The resulting polyphenylene ethers can advantageously exhibit high molecular weights and narrow molecular weight distributions, as well as reduced levels of biphenyl and quinone by-products.

Accordingly, one aspect of the present disclosure is a method of preparing a polyphenylene ether. In one embodiment, the method comprises feeding the reaction mixture into a continuous flow reactor. The components of the reaction mixture can be pre-combined or separately fed into the reactor to provide the reaction mixture in the reactor.

ContinuousThe flow reactor allows for intense heat and mass transfer between multiple phases while providing limited back mixing of the phases in the direction of flow. The volumetric mass transfer coefficient preferably exceeds 0.1s^-1For example, 0.1 to 5s^-1. The heat transfer per unit volume is preferably greater than 500m^-1. The flow reactor can also have a flow rate of 10 to 1500m^-1Surface area to volume ratio of (a). Suitable continuous flow reactors can include, but are not limited to, microreactors and millireactors. The continuous Flow reactor can be a commercially available Flow reactor, e.g., Advanced-Flow^TMReactor from Corning Inc., modular microreactor System (Modular Microreaction System), L naza Flowplate^TM，ART^TMPlate reactor and Miprowa^TMFrom EhrfeldMikrotechnik BTS GmbH; qmix^TMMicroreactor System from Cetoni; L ABTRIX^TMSTART，LABTRIX^TMS1，KILOFLOW^TMAnd P L ANTRIX^TMFrom Chemtrix; HTM^TM，MR-LAB^TM，MR PILOT^TMAnd XX L^TMSERIES from L title Things Factory, Asia^TMFlow chemistry system, from Syrris; KeyChem^TM；CYTOS-200^TMAnd CYTOS-2000^TMFrom YMC, AMaR-2^TM(ii) a And AMaR-4P^TMIn a specific non-limiting example, an exemplary inner diameter of the reactor can be 0.01 to 10mm, or 0.05 to 8mm, or 0.1 to 5 mm.

The reaction mixture comprises phenol, a transition metal catalyst, and an organic solvent. The phenol may be a monohydric phenol having the structure

Wherein Q¹Is independently at each occurrence halogen, unsubstituted or substituted C_1-12Primary or secondary hydrocarbon radical, C_1-12Mercapto group, C_1-12Hydrocarbyloxy or at least two carbon atoms separatedC for opening halogen and oxygen atoms_2-12A halohydrocarbyloxy group; and wherein each occurrence of Q²Independently hydrogen, halogen, unsubstituted or substituted C_1-12Primary or secondary hydrocarbon radical, C_1-12Mercapto group, C_1-12Hydrocarbyloxy or C having at least two carbon atoms separating halogen and oxygen atoms_2-12A halohydrocarbyloxy group. In some embodiments, each occurrence of Q¹Is methyl, each occurrence of Q²Is hydrogen and the phenol is 2, 6-xylenol (also known as dimethylphenol). In some embodiments, Q¹Is methyl at each occurrence, and Q²Is hydrogen and the other occurrence is methyl, and the phenol is 2,3, 6-trimethylphenol.

Suitable transition metal catalysts for use in the synthesis of polyphenylene ethers include those containing catalyst metals such as manganese, chromium, copper and combinations thereof. Among the metal complex catalysts, copper complex catalysts comprising secondary alkanediamine ligands are preferably used. The copper source of the copper complex comprising secondary alkanediamine can comprise salts of copper or cuprous ions, including halides, oxides, and carbonates. Alternatively, the copper can be provided in the form of a preformed salt of the alkanediamine ligand. Preferred copper salts include cuprous halides, cupric halides, and combinations thereof. Particularly preferred are cuprous bromide, cupric bromide, and combinations thereof.

Preferred copper complex catalysts comprise secondary alkanediamine ligands. Suitable secondary alkanediamine ligands are described in U.S. Pat. No. 4,028,341 to Hay and are represented by the formula

R^b—NH—R^a—NH—R^c

Wherein R is^aIs a substituted or unsubstituted divalent residue in which two or three aliphatic carbon atoms form the closest bond between two diamine nitrogen atoms; and R is^bAnd R^cEach independently is isopropyl or substituted or unsubstituted C_4-8A tertiary alkyl group. R^aExamples of (A) include ethylene, 1, 2-propylene, 1, 3-propylene, 1, 2-butene, 1, 3-butene, 2, 3-butene, the various pentene isomers having two to three carbon atoms separated by a free valence, styrene, toluylene, 2-phenyl-1, 2-propylene, cycloHexylethylene, 1, 2-cyclohexene, 1, 3-cyclohexene, 1, 2-cyclopropene, 1, 2-cyclobutene, 1, 2-cyclopentene, and the like. Preferably R^aIs ethylene. R^bAnd R^cExamples of (a) can include isopropyl, tert-butyl, 2-methyl-but-2-yl, 2-methyl-pent-2-yl, 3-methyl-pent-3-yl, 2, 3-dimethyl-but-2-yl, 2, 3-dimethylpent-2-yl, 2, 4-dimethylpent-2-yl, 1-methylcyclopentyl, 1-methylcyclohexyl, and the like. R^bAnd R^cA highly preferred example of (a) is tert-butyl. An exemplary secondary alkanediamine ligand is N, N' -di-tert-butylethylenediamine (DBEDA). A suitable molar ratio of copper to secondary alkanediamine is 1:1 to 1:5, preferably 1:1 to 1:3, more preferably 1:1.5 to 1:2.

Preferred copper complex catalysts comprising secondary alkanediamine ligands may further comprise a secondary monoamine. Suitable secondary monoamine ligands are described in co-assigned U.S. Pat. No. 4,092,294 to Bennett et al and are represented by the formula

R^d—NH—R^e

Wherein R is^dAnd R^eEach independently is substituted or unsubstituted C_1-12Alkyl, preferably substituted or unsubstituted C_3-6An alkyl group. Examples of secondary monoamines include di-N-propylamine, diisopropylamine, di-N-butylamine, di-sec-butylamine, di-tert-butylamine, N-isopropyl-tert-butylamine, N-sec-butyl-tert-butylamine, di-N-pentylamine, bis (1, 1-dimethylpropyl) amine, and the like. A highly preferred secondary monoamine is di-n-butylamine (DBA). A suitable molar ratio of copper to secondary monoamine is 1:1 to 1:10, preferably 1:3 to 1:8, more preferably 1:4 to 1: 7.

Preferred copper complex catalysts comprising secondary alkanediamine ligands may further comprise a tertiary monoamine. Suitable tertiary monoamine ligands are described in the above-mentioned Hay U.S. patent 4,028,341 and Bennett U.S. patent 4,092,294 and include heterocyclic amines and certain trialkylamines characterized by an amine nitrogen attached to at least two groups having a small cross-sectional area. In the case of trialkylamines, it is preferred that at least two of the alkyl groups are methyl groups and the third is a primary C_1-8Alkyl or secondary C_3-8An alkyl group. It is particularly preferred that the third substituent has not more than four carbon atoms. A highly preferred tertiary amine is dimethylbutylamine(DMBA). Suitable molar ratios of copper to tertiary amine are less than 1:20, preferably less than 1:15, preferably from 1:1 to less than 1:15, more preferably from 1:1 to 1: 12.

The molar ratio of the metal complex catalyst (measured by the mole number of the metal) to the phenol is preferably 1:50 to 1:400, more preferably 1:100 to 1:200, and still more preferably 1:100 to 1: 180.

The reaction carried out in the presence of a metal complex catalyst can optionally be carried out in the presence of bromide ions. It has been mentioned that bromide ions can be provided in the form of cuprous bromide or cupric bromide salts. Bromide ions can also be provided by the addition of 4-bromophenol, such as 2, 6-dimethyl-4-bromophenol. Other bromide ions can be provided in the form of hydrobromic acid, alkali metal bromides, or alkaline earth metal bromides. Sodium bromide and hydrobromic acid are highly preferred bromide sources. The suitable ratio of bromide ions to copper ions is 2 to 20, preferably 3 to 20, and more preferably 4 to 7.

The reaction mixture also contains an organic solvent. Suitable organic solvents include alcohols, ketones, aliphatic and aromatic hydrocarbons, chlorinated hydrocarbons, nitrohydrocarbons, ethers, esters, amides, mixed ether-esters, sulfoxides, and the like, provided that they do not interfere with or participate in the oxidation reaction. Preferably the solvent is selected to avoid any precipitation in the reactor. The organic solvent can include, for example, toluene, benzene, xylene, chlorobenzene, o-dichlorobenzene, nitrobenzene, trichloroethylene, dichloroethane, dichloromethane, chloroform, tetrachloroethane, or combinations thereof. Preferred solvents include aromatic hydrocarbons. In some embodiments, the organic solvent comprises toluene.

Suitable starting concentrations of phenol can be 5 wt% to 35 wt%, or 5 wt% to 15 wt%, preferably 5 wt% to 10 wt%, more preferably 6 wt% to 10 wt%, or 15 wt% to 35 wt%, or 20 wt% to 32 wt%, based on the total weight of phenol and solvent. All phenol can be added at the beginning of the reaction. Alternatively, the phenol can be added in discrete or continuous amounts during the course of the reaction.

The reaction mixture can optionally further comprise one or more additional components including a lower alkanol or diol, a minor amount of water or a phase transfer agent. It is generally not necessary to remove the reaction by-product water during the course of the reaction. Is suitable forThe phase transfer agent of (a) can include, for example, a quaternary ammonium compound, a quaternary phosphonium compound, a tertiary sulfonium compound, or a combination thereof. Preferably the phase transfer agent can have the formula (R)³)₄Q⁺X, wherein each R³Are the same or different and are C_1-10An alkyl group; q is a nitrogen or phosphorus atom; x is a halogen atom or C_1-8Alkoxy or C_6-18An aryloxy group. Exemplary phase transfer catalysts include (CH)₃(CH₂)₃)₄NX、(CH₃(CH₂)₃)₄PX、(CH₃(CH₂)₅)₄NX、(CH₃(CH₂)₆)₄NX、(CH₃(CH₂)₄)₄NX、CH₃(CH₃(CH₂)₃)₃NX and CH₃(CH₃(CH₂)₂)₃NX, wherein X is Cl^-，Br^-，C_1-8Alkoxy or C_6-18An aryloxy group. An effective amount of phase transfer agent can be 0.1 wt% to 10 wt% or 0.5 wt% to 2 wt% based on the weight of the reaction mixture. In a specific embodiment, a phase transfer agent is present and comprises N, N' -didecyldimethylammonium chloride.

In some embodiments, the reaction mixture can optionally further comprise a dihydric phenol, preferably 2,2',6,6' -tetramethylbisphenol a, 2',6,6' -tetramethylbisphenol, 2',3,3',5,5' -hexamethyl- [1,1' -biphenyl ] -4,4' -diol, or a combination thereof. When present, the dihydric phenol can be included in the reaction mixture in an amount of 1 wt% to 20 wt%, or 1 wt% to 10 wt%, based on the total weight of the reaction mixture.

The process further comprises feeding air into the continuous flow reactor containing the reaction mixture. The feeding of air can be carried out in an amount effective to provide phenol to oxygen in a molar ratio of 1:1 to 1:1.2, preferably 1: 1.1. In some embodiments, the air can be a combination comprising oxygen and nitrogen. In some embodiments, the air comprises less than 50% oxygen, or less than 40% oxygen, or at least 5% oxygen or at least 10% oxygen. Within this range, the air contains 15% to 25% or 19% to 22% oxygen. In some embodiments, the balance is nitrogen. The air can contain less than 0.1ppm hydrocarbons.

Upon feeding the reaction mixture and air into the continuous flow reactor, the reaction mixture is capable of undergoing oxidative polymerization to form the desired polyphenylene ether. The polymerization can be carried out at a temperature of 20 to 60 ℃, preferably 25 to 55 ℃, and more preferably 30 to 50 ℃. Advantageously, the residence time of the reaction mixture in the continuous flow reactor can be less than or equal to 30min, or less than or equal to 15min, preferably from 3 to 20min, more preferably from 3 to 15 min. Oxidative polymerization can be carried out at a pressure of greater than 150kPa, preferably greater than or equal to 200kPa, more preferably greater than or equal to 500kPa, still more preferably greater than or equal to 1000 kPa. In some embodiments, the pressure can be less than or equal to 2000kPa, or less than or equal to 1500 kPa. In one advantageous feature, the continuous flow reactor of the present disclosure can have a significantly reduced oxygen headspace compared to other conventional reactors, and thus the reaction can be carried out at higher temperatures without including safety issues.

When the target intrinsic viscosity is reached, the reaction can be terminated by stopping the addition of oxygen. Other suitable methods of terminating the reaction include the addition of mineral or organic acids such as acetic acid, or the addition of chelating agents, as described in more detail below.

The method can further comprise recovering the copper catalyst using an aqueous chelating agent solution. Suitable techniques for recovering the catalyst metal from the metal complex catalyst include those described in co-assigned U.S. Pat. No. 3,838,102 to Bennett et al, U.S. Pat. No. 3,951,917 to Florryan et al, and U.S. Pat. No. 4,039,510 to Cooper et al. These techniques include the addition of one or more chelating agents to coordinate the catalyst metal and facilitate its separation from the polyphenylene ether product. A preferred method for removing catalyst metals from polyphenylene ether products is described in U.S. application No. 09/616,737. The process dispenses with multiple rinses with complexing agent, including removal of catalyst from the polymerization mixture by mixing the polymerization mixture with the complexing agent and liquid/liquid centrifuging the heterogeneous mixture. Water is then added to the polymer phase prior to a subsequent liquid/liquid centrifugation process. In general, suitable chelating agents include polyfunctional carboxylic acid-containing compounds such as citric acid, tartaric acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid, ethylenediaminedisuccinic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, and the like. These chelating agents can be used as their free acids or, for example, as their salts of alkali metal, alkaline earth metal and nitrogen-containing cations. Preferred chelating agents include nitrilotriacetic acid, ethylenediaminetetraacetic acid and salts thereof. Suitable molar ratios of chelating agent to catalyst metal are 1:1 to 5:1, preferably 1.1:1 to 3:1, more preferably 1:1.5 to 1: 2.5.

The method can further comprise, for example, isolating the polyphenylene ether by precipitation. Precipitation of polyphenylene ether can be induced by appropriate selection of the above reaction solvent or addition of an antisolvent to the reaction mixture. Suitable antisolvents include lower alkanols having one to about ten carbon atoms, acetone, and hexane. The preferred antisolvent is methanol. The anti-solvent may be used in a concentration range relative to the organic solvent, and the optimum concentration depends on the characteristics of the organic solvent and the anti-solvent, as well as the concentration and intrinsic viscosity of the polyphenylene ether product. It has been found that when the organic solvent is toluene and the anti-solvent is methanol, a toluene to methanol weight ratio of 50:50 to 80:20 is suitable, preferably a ratio of 60:40 to 70:30, more preferably 63:37 to 67: 33. These preferred and more preferred ratios are suitable for producing the desired powder morphology of the isolated polyphenylene ether resin without producing filiform powder or excessive amounts of powder fines.

The method can optionally include pre-concentrating the reaction mixture prior to adding the anti-solvent. Although preconcentration to a high degree of polyphenylene ether of relatively low intrinsic viscosity is not possible, for example, preconcentration of 15 wt% polyphenylene ether is possible. Any suitable pre-concentration method can be used. For example, pre-concentration is carried out by preheating the solution above atmospheric boiling point at a moderate elevated pressure above one atmosphere (so that no boiling occurs in the heat exchanger) and then flashing the solution to a lower pressure and temperature whereby most of the toluene is vaporized and the heat of vaporization required is provided by the heat transferred in the heat exchanger as sensible heat of the solution.

The isolated polyphenylene ether can have an intrinsic viscosity of greater than or equal to 0.04 to 2 deciliters per gram, preferably 0.06 to 2 deciliters per gram, more preferably 0.8 to 2 deciliters per gram, even more preferably 0.08 to 1.6 deciliters per gram, or 0.06 to 1.0 deciliters per gram, measured in chloroform at 25 ℃ using an Ubbelohde viscometer.

The isolated polyphenylene ether can also have a degree of dispersion of less than 3, for example, 1.2 to 2.9, or 1.5 to 2.7. The degree of dispersion can be determined by gel permeation chromatography using chloroform against a polystyrene standard.

In some embodiments, polyphenylene ethers prepared according to the methods described herein can advantageously have reduced biphenyl content, quinone content, or both. For example, the polyphenylene ether can have a combined biphenyl and quinone content of less than 0.5 wt%, based on the weight of phenol used in the oxidative polymerization.

Thus, polyphenylene ethers prepared according to the above-described process represent another aspect of the present disclosure. The polyphenylene ether can comprise repeating structural units having the formula

Wherein Q¹And Q²Each occurrence of (a) is as defined above. The hydrocarbyl residue can also contain one or more carbonyl groups, amino groups, hydroxyl groups, or the like, or it can contain heteroatoms within the backbone of the hydrocarbyl residue. As an example, Q¹Can be di-n-butylaminomethyl formed by reacting the terminal 3, 5-dimethyl-1, 4-phenyl with the di-n-butylamine component of an oxidative polymerization catalyst.

The polyphenylene ether can comprise molecules having aminoalkyl-containing end group(s) located generally ortho to the hydroxy group. Also frequently present are tetramethyl diphenoquinone (TMDQ) end groups, typically obtained from a 2, 6-dimethylphenol-containing reaction mixture in the presence of by-product tetramethyl diphenoquinone. In some embodiments, the polyphenylene ether can be substantially free of quinone end groups. For example, the polyphenylene ether can include less than 1% quinone end groups. The polyphenylene ether can be in the form of a homopolymer, copolymer, graft copolymer, ionomer, or block copolymer, and combinations thereof.

Compositions and articles comprising polyphenylene ether made by the above-described process represent another aspect of the present disclosure. For example, the polyphenylene ether made by the methods herein can be suitable for use in forming a thermoplastic composition, which can optionally comprise at least one of a thermoplastic polymer other than polyphenylene ether and an additive composition comprising one or more additives.

Polyphenylene ethers can be shaped into articles by molding, extrusion or molding. The article can be formed from the composition by methods including, for example, injection molding, injection compression molding, gas-assisted injection molding, rotational molding, blow molding, compression molding, and the like. In some embodiments, the article can be formed by injection molding.

The disclosure is further illustrated by the following non-limiting examples.

Examples

The materials used in the following examples are described in table 1.

TABLE 1

The effect of pressure and the use of air as an oxidant source was first verified for a copolymer of DMP and TMBPA. The reaction mixture used in this example was prepared according to the composition in table 2. The amounts of each component are given in weight percent based on the total weight of the reaction mixture. The components are stirred well to ensure dissolution prior to introduction into the reactor.

TABLE 2

Components	Weight (g)	Number of moles	Feeding of the feedstockIn weight percent
				DMP	69.17	0.57	24.36
TMBPA	14.62	0.05	5.15
				Cu2O	0.05	0.0004	0.02
HBr	0.65	0.01	0.23
				DMBA	1.97	0.02	0.69
DBA	1.00	0.01	0.35
				Diamine mixtures1	0.48	0.00	0.17
Toluene	196.00	2.13	69.03

¹The diamine mixture comprised 0.14 grams DBEDA, 0.04 grams DDAC, and 0.3 grams toluene

In comparative examples 1 and 2, the above reaction mixture was used in a batch polymerization at 42 ℃ with pure oxygen as the oxidant, these polymerizations were conducted at atmospheric pressure (i.e., 1 atmosphere or 101.325 kPa.) the results of this polymerization are shown in Table 3 for comparative examples 1 and 2, the weight percent of DMP in the reaction mixture during the polymerization was determined using HP L C for all flow reactions, Mettler Toledo ReactIR with a fiber optic probe and Dicomp ATR crystals was used for all flow reactions^TM45m and Mettler Toledo ReactIR with microfluidic cell and diamond ART crystal^TM45m, the weight percentage of DMP in the reaction mixture at different times was determined by on-line infrared spectroscopy. Analyzing 1350-1200 cm according to the calibration curve^-1Range of 1260cm^-1The values were plotted as a linear regression using the obtained HP L C data to construct a calibration curve for determining DMP concentration.

TABLE 3

Comparative examples 3 to 5 in table 4 below show the copolymerization of DMP and TMBPA in a continuous flow reactor using the reaction mixture shown in table 2 at a temperature of 42 ℃ with pure oxygen as oxidant. An advanced flow reactor AFR obtained from Corning was used for flow polymerization. The flow reactor used is a plate reactor with a plurality of plates arranged in series to provide a sufficient reactor volume.

The polymerizations of comparative examples 3-5 were conducted in a flow reactor at a liquid flow rate of 12m L/min and a gas (atmospheric oxygen) flow rate of 250m L/min comparative examples 3-5 were conducted at atmospheric pressure (i.e., 1 atmosphere or 101.325 kPa.) the weight percent of DMP in the reaction mixture at various times was determined by on-line infrared spectroscopy, as described above.

TABLE 4

Examples 1-2 in Table 5 below show the copolymerization of DMP and TMBPA in a continuous flow reactor using the reaction mixture of Table 2 with air as the oxidant and a temperature of 42 deg.C in example 1, the reaction was carried out at a pressure of 5 bar (500kPa) in example 2, the reaction was carried out at a pressure of 10 bar (1000kPa) in example 2 these polymerizations in a flow reactor were carried out at a liquid flow rate of 12m L/min and a gas flow rate of 250m L/min the weight percent of DMP in the reaction mixture at different times was determined by on-line infrared spectroscopy as described above.

TABLE 5

	Example 1	Example 2
			Residence time (min)	DMP(wt％)	DMP(wt％)
0	23.69	23.33
			3.8	5.28	3.52
7.5	1.79	3.31
			11.25	0.52

As can be seen from the data given in tables 3-5, air can be used as the oxidant using the flow reactor. In addition, the polymerization can be carried out under pressure to provide short reaction times.

The effect of pressure and the use of air as an oxidant was also demonstrated for DMP homopolymer. The reaction mixtures used in these examples were prepared according to the compositions described in table 6. The amounts of each component are given in weight percent based on the total weight of the reaction mixture. The components are stirred well to ensure dissolution prior to introduction into the reactor.

TABLE 6

Components	Weight (g)	Number of moles	Weight percent in the feed
				DMP	65.00	0.53	23.67
Cu2O	0.08	0.0005	0.03
				HBr	0.43	0.01	0.16
DMBA	2.11	0.02	0.77
				DBA	0.62	0.00	0.23
Diamine mixtures1	0.36	0.00	0.13
				Toluene	206.00	2.24	75.02

¹The diamine mixture comprised 0.11 grams of DBEDA, 0.03 grams of DDAC, and 0.22 grams of toluene

In comparative example 6, the above reaction mixture was used in a batch polymerization with pure oxygen as the oxidizing agent and a temperature of 42 ℃. The polymerization reaction is carried out at atmospheric pressure (i.e., 1 atmosphere or 101.325 kPa). The results of this polymerization are shown in table 7. The weight percent of DMP in the reaction mixture at various times was determined by on-line infrared spectroscopy, as described above.

TABLE 7

Comparative example 7 in Table 8 below shows homopolymerization of DMP in a continuous flow reactor using pure oxygen as the oxidant and the reaction mixture of Table 6 at a temperature of 42 deg.C this polymerization in a flow reactor was carried out at a liquid flow rate of 12m L/min and a gas flow rate of 250m L/min comparative example 7 was carried out at atmospheric pressure (i.e., 1 atmosphere or 101.325 kPa.) the weight percent of DMP in the reaction mixture at various times was determined by on-line infrared spectroscopy, as described above.

TABLE 8

	Comparative example 7
		Residence time, min	DMP(wt％)
0	22.76
		3.75	13.46
7.5	4.88
		11.25	1.19
15	0.31

Examples 3-4 in Table 9 below show DMP homopolymerization in a continuous flow reactor with air as the oxidant and a temperature of 42 ℃ using the reaction mixture of Table 6. in example 3, the reaction was carried out at a pressure of 5 bar (500 kPa.) in example 4, the reaction was carried out at a pressure of 10 bar (1000 kPa.) these polymerizations in a flow reactor were carried out at a liquid flow rate of 12m L/min and a gas flow rate of 250m L/min.

TABLE 9

	Example 3	Example 4
			Residence time, min	DMP(wt％)	DMP(wt％)
0	23.69	22.59
			3.75	5.28	2.2
7.5	1.79	1.68
			11.25	0.52	0.06

As can be seen from the data presented in tables 7-9, a flow reactor was used with air as the oxidant for DMP homopolymerization. In addition, the polymerization can be carried out under pressure to give short reaction times.

Another advantage of the present process using a flow reactor is the low formation of by-products (e.g., quinones and biphenyls). Table 10 below shows a comparison of the weight percent of by-products (tetramethyldiphenoquinone (TMDQ) units and Tetramethylbiphenyl (TMPA) units) relative to the weight of the DMP (i.e., the initial weight of DMP used at the start of the polymerization). Copolymers of DMP and TMBPA were prepared according to the batch process (comparative example 8) and the flow process (example 5). In both comparative example 8 and comparative example 9, oxygen was used as the oxidizing agent, and the reaction was carried out at atmospheric pressure. Other reaction conditions were the same as described above.

Watch 10

Example 5 in Table 11 below shows the homopolymerization of DMP in a batch reactor using the reaction mixture of Table 2 in which air is the oxidant and the temperature is 42 deg.C, the polymerization was conducted at atmospheric pressure (i.e., 1 atmosphere or 101.325kPa), the weight percentages of DMP, TMBP and TMDQ in the reaction mixture at various times were determined by HP L C.

TABLE 11

As shown in tables 10 and 11, the amount of by-products (e.g., quinone and biphenyl by-products) produced by C-C coupling can be reduced by nearly half when using a flow reactor.

Table 12 below shows the weight average molecular weight (Mw), the dispersity (PDI) and the Intrinsic Viscosity (IV) of the polymers prepared by the process of comparative example 1, comparative example 7, example 1 and example 2. Intrinsic viscosity was determined using an ubpelohde viscometer at 25 ℃ in chloroform, and Mw and PDI were determined using gel permeation chromatography using chloroform versus polystyrene standards.

TABLE 12

Examples	Mw	PDI	IV
				Comparative example 1	4381	2.49	0.09
Comparative example 7	3194	2.03	0.08
				Example 1	2540	1.9	0.085
Example 2	3510	2.05	0.09

The present disclosure further includes the following aspects.

Aspect 1: a method for preparing a polyphenylene ether, the method comprising: feeding air into a continuous flow reactor containing a reaction mixture comprising phenol, a transition metal catalyst, and an organic solvent; and oxidizing the polymerization reaction mixture at a temperature of 20 to 60 ℃, preferably 25 to 55 ℃, more preferably 30 to 50 ℃ and a pressure of more than 150kPa, preferably more than or equal to 200kPa, more preferably more than or equal to 500kPa, more preferably more than or equal to 1000kPa to form a polyphenylene ether; wherein the residence time of the reaction mixture in the continuous flow reactor is less than or equal to 30min, preferably 3 to 20min, more preferably 3 to 15 min.

Aspect 2: the process of aspect 1, wherein the continuous flow reactor is characterized by a volumetric mass transfer coefficient of 0.1 to 5s^-1And the ratio of the surface area to the volume is 10 to 1500m^-1。

Aspect 3: the method of any of aspects 1-2, wherein the phenol comprises 2, 6-dimethylphenol, 2,3, 6-trimethylphenol, or a combination thereof, preferably 2, 6-dimethylphenol.

Aspect 4: the method of any of aspects 1 to 3, wherein the transition metal catalyst is a copper-amine catalyst, preferably comprising copper ions and a hindered secondary amine; preferably wherein the hindered secondary amine has the formula R_bHN-R_a-NHR_cWherein R is_aIs C_2-4Alkylene or C_3-7Cycloalkylene, and R_bAnd R_cIs isopropyl or C_4-8Tertiary alkyl groups in which only the α -carbon atom has no hydrogen atoms and at least two and no more than three carbon atoms separate two nitrogen atoms, more preferably wherein the secondary hindered amine is di-t-butylethylenediamine.

Aspect 5: the method of any one of aspects 1 to 4, wherein the organic solvent comprises toluene, benzene, xylene, chlorobenzene, o-dichlorobenzene, nitrobenzene, trichloroethylene, dichloroethane, dichloromethane, chloroform, tetrachloroethane, or a combination thereof, preferably toluene.

Aspect 6: the method of any one or more of aspects 1 to 5, wherein the reaction mixture further comprises a dihydric phenol, preferably 2,2',6,6' -tetramethylbisphenol A, 2,2',6,6' -tetramethylbiphenol, 2,2',3,3',5,5' -hexamethyl- [1,1' -biphenyl ] -4,4' -diol, or a combination thereof.

Aspect 7: the method of any of aspects 1 to 6, wherein the reaction mixture further comprises one or more of a secondary monoamine, a tertiary monoamine, or a combination thereof, preferably wherein the secondary monoamine comprises di-N-butylamine and the tertiary monoamine comprises N, N-dimethylbutylamine; a source of bromide ions, preferably hydrobromic acid; and a phase transfer agent, preferably wherein the phase transfer agent comprises a quaternary ammonium compound, a quaternary phosphonium compound, a tertiary sulfonium compound, or a combination thereof, more preferably wherein the phase transfer agent comprises N, N' -didecyldimethylammonium chloride.

Aspect 8: the process of any of aspects 1 to 7, wherein feeding air into the reactor is carried out in an amount effective to provide a molar ratio of phenol to oxygen of from 1:1 to 1:1.2, preferably 1: 1.1.

Aspect 9: the method of any one of aspects 1 to 8, further comprising separating the polyphenylene ether from the reaction mixture.

Aspect 10: the method according to any one of aspects 1 to 9, wherein the polyphenylene ether has an intrinsic viscosity of 0.04 to 2 deciliters/gram, a polydispersity index of less than 3, or both.

Aspect 11: the method of any of aspects 1 to 10, wherein the polyphenylene ether has a combined biphenyl and quinone content of less than 0.5 wt% based on the weight of phenol used in the oxidative polymerization.

Aspect 12: a polyphenylene ether prepared by the method of any one or more of aspects 1 to 11.

Aspect 13: the polyphenylene ether of aspect 12, wherein the polyphenylene ether has a combined biphenyl and quinone content of less than 0.5 wt%, based on the weight of phenol used in the oxidative polymerization.

Aspect 14: an article comprising the polyphenylene ether of aspect 12 or 13.

The compositions, methods, and articles can alternatively comprise, consist of, or consist essentially of any suitable material, step, or component disclosed herein. The compositions, methods, and articles can additionally or alternatively be formulated to be free or substantially free of any material (or species), step, or component that is not necessary to achieve the described function or purpose of the composition, method, and article.

All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. "combination" includes blends, mixtures, alloys, reaction products, and the like. The terms "first," "second," and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The terms "a," "an," and "the" do not denote a limitation of quantity, and should be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Unless expressly stated otherwise, "or" means "and/or. Reference throughout the specification to "some embodiments," "an embodiment," and so forth, means that a particular element described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. As used herein, the term "a combination thereof" includes one or more of the listed elements and is open-ended, thereby permitting the presence of one or more unnamed similar elements. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments.

Unless stated to the contrary herein, all test criteria are the most recent criteria that come into effect from the filing date of the present application, or, if priority is required, appear to be the filing date of the earliest priority application for the test criteria.

Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term in the present application takes precedence over the conflicting term in the incorporated reference.

Each compound is described using standard nomenclature. For example, any position not substituted by any indicated group is understood to have its valency filled by a bond as indicated, or a hydrogen atom. A dash ("-") that is not between two letters or symbols is used to indicate a point of attachment for a substituent. For example, -CHO is attached through the carbon of the carbonyl group.

As used herein, the term "hydrocarbyl", whether used by itself, or as a prefix, suffix, or fragment of another term, refers to a residue that contains only carbon and hydrogen. The residue can be aliphatic or aromatic, straight chain, cyclic, bicyclic, branched, saturated, or unsaturated. It can also contain combinations of aliphatic, aromatic, straight chain, cyclic, bicyclic, branched, saturated, and unsaturated hydrocarbon moieties. However, when the hydrocarbyl residue is described as substituted, it may optionally contain heteroatoms over and above the carbon and hydrogen members of the substituent residue. Thus, when specifically described as substituted, the hydrocarbyl residue can also contain one or more carbonyl groups, amino groups, hydroxyl groups, or the like, or it can contain heteroatoms within the backbone of the hydrocarbyl residue. The term "alkyl" refers to a branched or straight chain unsaturated aliphatic hydrocarbon group, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, sec-pentyl, and n-hexyl and sec-hexyl. "alkenyl" refers to a straight or branched chain monovalent hydrocarbon group having at least one carbon-carbon double bond (e.g., vinyl (-HC ═ CH)₂)). "alkoxy" refers to an alkyl group attached via an oxygen (i.e., alkyl-O-), e.g., methoxy, ethoxy, and sec-butoxy. "alkylene" refers to a straight or branched chain saturated divalent aliphatic hydrocarbon radical (e.g., methylene (-CH)₂-) or propylene (- (CH)₂)₃-). "Cycloalkylene" refers to a divalent cycloalkylene-C_nH_2n-xWherein x is the number of hydrogens substituted with cyclization. "cycloalkenyl" refers to a monovalent group having one or more rings and one or more carbon-carbon double bonds in the ring, where all ring members are carbon (e.g., cyclopentyl and cyclohexyl). "aryl" refers to an aromatic hydrocarbon group containing the indicated number of carbon atoms, such as phenyl, tropone, indanyl or naphthyl. "arylene" refers to a divalent aromatic radical. "Alkylarylene" refers to an arylene group substituted with an alkyl group. "arylalkylene" refers to an alkylene group substituted with an aryl group (e.g., benzyl). The prefix "halo" refers to a group or compound that includes one or more fluoro, chloro, bromo, or iodo substituents. Combinations of different halogen groups (e.g., bromine and fluorine) or only chlorine groups may be present. The prefix "hetero" means that the compound or group includes at least one ring member that is a heteroatom (e.g., 1,2, or 3 heteroatoms), wherein the heteroatoms are each independently N, O, S, Si or P. "substituted" means that the compound or group is substituted with at least one (e.g., 1,2, 3, or 4) substituent, each of which can be independently C_1-9Alkoxy radical, C_1-9Haloalkoxy, nitro (-NO)₂) Cyano (-CN), C_1-6Alkylsulfonyl (-S (═ O)₂Alkyl), C_6-12Arylsulfonyl (-S (═ O)₂-aryl), mercapto (-SH), thiocyano (-SCN), tosyl (CH)₃C₆H₄SO₂-)、C_3-12Cycloalkyl radical, C_2-12Alkenyl radical, C_5-12Cycloalkenyl radical, C_6-12Aryl radical, C_7-13Arylalkylene radical, C_4-12Heterocycloalkyl and C_3-12Heteroaryl groups replace hydrogen, provided that the normal valency of the substituted atom is not exceeded. The number of carbon atoms indicated in the group does not include any substituents. For example, -CH₂CH₂CN is C substituted by a nitrile₂An alkyl group.

While particular embodiments have been described, applicant or other skilled in the art may conceive of presently or presently unforeseen alternatives, modifications, variations, improvements, and substantial equivalents. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications, variations, improvements, and substantial equivalents.

Claims (14)

1. A method for preparing a polyphenylene ether, the method comprising:

feeding air into a continuous flow reactor containing a reaction mixture comprising phenol, a transition metal catalyst, and an organic solvent; and

oxidatively polymerizing the reaction mixture at a pressure of 20 to 60 ℃, preferably 25 to 55 ℃, more preferably 30 to 50 ℃, and greater than 150kPa, preferably greater than or equal to 200kPa, more preferably greater than or equal to 500kPa, more preferably greater than or equal to 1000kPa to form a polyphenylene ether;

wherein the residence time of the reaction mixture in the continuous flow reactor is less than or equal to 30min, preferably from 3 to 20min, more preferably from 3 to 15 min.

2. The process of claim 1, wherein the continuous flow reactor is characterized by a volumetric mass transfer coefficient of 0.1 to 5s^-1And the ratio of the surface area to the volume is 10 to 1500m^-1。

3. The method of any one of claims 1-2, wherein the phenol comprises 2, 6-dimethylphenol, 2,3, 6-trimethylphenol, or a combination thereof.

4. A process according to any one of claims 1 to 3, wherein the transition metal catalyst is a copper amine catalyst, preferably comprising copper ions and a hindered secondary amine,

preferably wherein the hindered secondary amine has the formula

R_bHN—R_a—NHR_c

Wherein R is_aIs C_2-4Alkylene or C_3-7Cycloalkylene, and R_bAnd R_cIs isopropyl or C_4-8Tertiary alkyl radicals in which only α -carbon atoms have no hydrogen atoms and at least two and not more than three carbon atoms divide two nitrogen atomsSeparating;

more preferably wherein the hindered secondary amine is di-t-butylethylenediamine.

5. The method of any one of claims 1 to 4, wherein the organic solvent comprises toluene, benzene, xylene, chlorobenzene, o-dichlorobenzene, nitrobenzene, trichloroethylene, dichloroethane, dichloromethane, chloroform, tetrachloroethane or a combination thereof, preferably toluene.

6. The method of any one or more of claims 1 to 5, wherein the reaction mixture further comprises a dihydric phenol, preferably 2,2',6,6' -tetramethylbisphenol A, 2',6-6' -tetramethylbisphenol, 2',3,3',5,5' -hexamethyl- [1,1' -biphenyl ] -4,4' -diol, or a combination thereof.

7. The process of any one of claims 1 to 6, wherein the reaction mixture further comprises one or more of:

a secondary monoamine, a tertiary monoamine, or a combination thereof, preferably wherein the secondary monoamine comprises di-N-butylamine and the tertiary monoamine comprises N, N-dimethylbutylamine;

a source of bromide ions, preferably hydrobromic acid; and

a phase transfer agent, preferably wherein the phase transfer agent comprises a quaternary ammonium compound, a quaternary phosphonium compound, a tertiary sulfonium compound, or a combination thereof, more preferably wherein the phase transfer agent comprises N, N' -decyldimethylammonium chloride.

8. A process according to any one of claims 1 to 7, wherein air is fed to the reactor at a flow rate effective to provide a molar ratio of phenol to oxygen in the range 1:1 to 1:1.2, preferably 1: 1.1.

9. The method according to any one of claims 1 to 8, further comprising separating the polyphenylene ether from the reaction mixture.

10. The method of any one of claims 1-9, wherein the polyphenylene ether has an intrinsic viscosity of 0.04-2 deciliters per gram measured in chloroform at 25 ℃ using an Ubbelohde viscometer, a polydispersity index of less than 3 measured relative to polystyrene standards using gel permeation chromatography with chloroform, or both.

11. The method according to any one of claims 1 to 10, wherein the polyphenylene ether has a combined biphenyl and quinone content of less than 0.5 wt%, based on the weight of phenol used in the oxidative polymerization.

12. A polyphenylene ether prepared by the method according to any one or more of claims 1 to 11.

13. The polyphenylene ether according to claim 12, wherein the polyphenylene ether has a combined biphenyl and quinone content of less than 0.5 wt% based on the weight of the phenol used in the oxidative polymerization.

14. An article comprising the polyphenylene ether of claim 12 or 13.